The necessity of turning a log prior to further processing has been a long standing requirement in most log processing machinery. Many types of turners have existed over time. Early ones required the log to stop forward motion during the turning motion. As machine throughput has increased it is more common now to use log turner designs that can turn the log during forward motion—so called flying log turners. One such common log turner was comprised of two opposing vertical spiked rolls that would move up/down opposite to each other such that the linear motion was translated into a rotary turn of the log as it was driven forward by these same spiked rolls. After each turn these rolls would need to reset to a home position in preparation for the next turn cycle. Other flying log turner designs also require this reset to home motion. If such turners do not perform this reset motion in applicant's experience there is a good chance that during the next turn cycle the log turner would run out of linear stroke and the turn would fail. As log processing speeds have increased the time of this ‘reset to home’ is more and more of a problem since at some point it would limit processing speeds.
Traditional log turners also have not proven to be very accurate when it comes to turning. This is a result of the in-direct nature of the rotation. Although the optimization computer calculates the required angle of turning very accurately this angle must be then recalculated as a distance of linear travel—a calculation based on the diameter of the log. Logs by their nature have highly irregular surfaces making this translation from rotary angle to linear travel not very accurate. To make matters worse there is more potential in these traditional designs for log slippage and the end result was that many logs were not being accurately turned. This then results in the ideal optimization the computer has calculated not being achieved—and then the yield of lumber not being as high as expected. Recent efforts to improve on this have incorporated some form of second scanning measurement of the rotary position along with a second ‘corrective’ turn but this is an expensive and only partially successful answer to the problem. The present invention by virtue of its X, Y and direct rotary motion provides more accurate positioning of the log in the optimized rotary orientation on the first turn cycle, negating the need for added complexity
In the prior art, applicant is aware of U.S. Pat. No. 5,622,213 which issued to McKelvie on Apr. 22, 1997 for a Flying Log Turner. As described by McKelvie, in any processing operation handling logs, the logs are generally carried on conveyor belts between processing equipment that performs specific tasks on the logs, the example given where logs are processed into sawed lumber after being fed past scanning equipment that determines the optimized orientation of the log for maximum recovery from log. McKelvie describes the use in the past of conventional flying vertical rolls, and proposes a flying log turner wherein a rotating group is mounted in a main frame, the housing having a passage therethrough to receive a log from an infeed conveyor, and in which gripping spike rolls are mounted adjacent the passage to grip a log passing through the passage. The spike rolls are mounted on the rotating group for movement with the housing. A drive motor rotates the rotating group through a selected angle to rotate the longitudinal axis of the log held in the spike rolls.